Catheter for uniform delivery of medication

ABSTRACT

The present invention provides a catheter for the delivery of fluid medication across an anatomical region. In accordance with one embodiment, the catheter comprises an elongated tube with a plurality of exit holes along an infusion section of the catheter, and an elongated flexible porous member residing within the tube and forming an annular space between the tube and the member. In accordance with other embodiments, the catheter includes a tube having a plurality of exit holes in a side wall of the tube. The exit holes may combine to form a flow-restricting orifice of the catheter. Advantageously, fluid within the catheter flows through all of the exit holes, resulting in uniform distribution of fluid within an anatomical region. In one particular embodiment, the catheter comprises a tube having elongated exit slots therein. In accordance with other embodiments, the catheter includes an elongated tubular member made of a porous membrane. The porous membrane is configured so that a fluid introduced into an open end of the tubular member will flow through side walls of the tubular member at a substantially uniform rate along a length of the tubular member. In accordance with other embodiments, the catheter includes an elongated “weeping” tubular coil spring attached to an end of, or enclosed within, a tube. Fluid within the spring and greater than or equal to a threshold pressure advantageously flows radially outward between the spring coils. Advantageously, the fluid is dispensed substantially uniformly throughout a length of the spring.

RELATED APPLICATIONS

[0001] This application is a continuation of U.S. patent applicationSer. No. 10/031,913, filed May 21, 2002, which is the national phase ofPCT/US00/19746, filed Jul. 19, 2000, which claims priority to U.S.patent application Ser. No. 09/363,228 filed Jul. 19, 1999, now U.S.Pat. No. 6,350,253, issued Feb. 26, 2002, the entireties of which areexpressly incorporated by reference herein and made a part of thisspecification.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] This invention generally relates to catheters and, in particular,to a catheter that delivers fluid medication uniformly across aninfusion section of the catheter.

[0004] 2. Description of the Related Art

[0005] Infusion catheters for delivery of fluid medication intoanatomical systems, such as the human body, are well known in the art.Such catheters generally include a flexible hollow tube inserted intosome region of the anatomy. The tube typically contains one or moreaxial lumens within which the fluid may flow. The proximal end of thecatheter tube is connected to a fluid source from which fluid isintroduced into the catheter tube. The fluid flows within one of thelumens under pressure supplied at the proximal end of the tube. For eachlumen, there are commonly provided one or more exit holes along aninfusion section near the distal end of the tube, for fluid to exit thetube. Such exit holes are created by piercing the side wall of thehollow tube.

[0006] In certain medical conditions, it is advantageous to deliverfluid medication to a plurality of sites within a wound area. Forinstance, some wounds which require pain medication may be incommunication with many nerve endings, rather than a single nerve trunk.One example of such a wound is a surgical incision. As stated above, itis known to provide a plurality of exit holes through which the fluidmedication exits the catheter tube. The exit holes may be provided atvarious axial and circumferential positions along the catheter tube inorder to control the position of the medication delivery sites. Anexample of a catheter having this configuration is disclosed in U.S.Pat. No. 5,800,407 to Eldor. Also, in some cases it is desirable todeliver such medication under low pressure, so that the fluid isdelivered at a relatively low rate. For example, some pain medicationsmust be delivered slowly to avoid toxicity and other side effects.Furthermore, in many cases it is desirable to dispense fluid medicationat a substantially uniform rate throughout the infusion section of thecatheter, so that the medication is evenly distributed throughout thewound area.

[0007] Unfortunately, a limitation of prior art catheters with multipleexit holes, such as the catheter taught by Eldor, is that during lowpressure delivery of fluid medication the fluid tends to exit onlythrough the exit hole(s) nearest to the proximal end of the infusionsection of the catheter tube. This is because fluids flowing through atube more readily exit through the exit holes offering the least flowresistance. The longer the flow path followed by the fluid in the lumen,the higher the flow resistance and pressure drop experienced by thefluid. The most proximal holes offer the least flow resistance andpressure drop. Therefore, the fluid tends to exit the catheter tubeprimarily through these exit holes. As a result, the fluid medication isdelivered only to a small region within the wound area. The tendency ofthe fluid to undesirably flow only through the most proximal exit holesdepends upon the hole size, the total number of exit holes, and the flowrate. As the hole size or number of holes increases, the fluid becomesmore likely to exit only through the most proximal holes. Conversely, asthe flow rate increases, the fluid becomes less likely to do so.

[0008] The tendency of the fluid to undesirably exit only through themost proximal holes of the catheter can in some cases be overcome byincreasing the flow rate or pressure of the fluid, which causes thefluid to flow through more of the exit holes of the catheter. Indeed, ifthe flow rate or pressure is sufficiently high, the fluid will flowthrough all of the exit holes. However, sometimes it is medicallydesirable to deliver medication at a relatively slow rate, i.e., at alow pressure. Also, even in those cases in which high pressure fluiddelivery is acceptable or desirable, prior art catheters do not providefor uniform fluid delivery along the infusion section of the catheter.Rather, the flow rate through the exit holes nearer to the proximal endof the infusion section tends to be greater than that through the exitholes nearer to the distal end. This is because the fluid passingthrough the more proximal holes experiences a lower flow resistance andpressure drop. In contrast, the fluid flowing through the more distalholes experiences greater flow resistance and pressure drop, andconsequently exits at a lower flow rate. The further distal the hole,the lower the exit flow rate of the fluid. As a result, there is anuneven distribution of medication throughout the wound area.

[0009] In another known type of infusion catheter, several lumens areprovided within a catheter tube. For each lumen, one exit hole isprovided by piercing a hole within the wall of the tube. The exit holesare provided at different axial positions along the infusion section ofthe catheter tube. In this manner, fluid medication may be delivered toseveral positions within the wound area. While this configuration offersimproved fluid distribution, it has some disadvantages. One disadvantageis that the fluid flow rates through the exit holes are not equal, sincethe more distal exit holes offer a greater flow resistance for the samereasons discussed above. Another disadvantage is that the number oflumens, and consequently the number of fluid exit holes, is limited bythe small diameter of the catheter tube. As a result, fluid may bedelivered only to a very limited number of positions within the woundarea. Yet another disadvantage is that the proximal ends of the lumensmust be attached to a complicated manifold which increases the cost ofmanufacturing the catheter.

[0010] An example of a catheter providing a more uniform dispensation offluid medication throughout an infusion section of the catheter isillustrated by U.S. Pat. No. 5,425,723 to Wang. Wang discloses aninfusion catheter including an outer tube, an inner tube concentricallyenclosed within the outer tube, and a central lumen within the innertube. The inner tube has a smaller diameter than the outer tube, so thatan annular passageway is formed therebetween. The outer tube has aplurality of evenly spaced exit holes defining the infusion section ofthe catheter. In use, fluid flowing within the central lumen passesthrough strategically positioned side holes within the side walls of theinner tube. In particular, the spacing between adjacent side holesdecreases along a length of the inner tube to induce more fluid to passthrough the more distal side holes. The fluid then flows longitudinallythrough the annular passageway before exiting through the exit holes inthe outer tube wall. In the annular passageway, the fluid can flow in adistal or proximal direction, depending on the location of the nearestexit hole in the outer tube. This configuration is provided to induce amore uniform exit flow rate of fluid from the catheter.

[0011] Unfortunately, the Wang catheter is only effective for relativelyhigh pressure fluid delivery. When used for relatively low pressurefluid delivery, the catheter disclosed by Wang does not provide uniformdispensation of fluid. Instead, the fluid tends to exit through the sideholes of the inner and outer tubes that are nearest to the proximal endof the infusion section of the catheter, since these holes offer theleast flow resistance. Even for high pressure fluid delivery, there areseveral limitations of this design. One limitation is that theconcentric tubes design is relatively complex and difficult tomanufacture. Both tubes must be flexible enough to permitmaneuverability through an anatomical system, yet the annular passagewaymust remain open so that fluid may flow uniformly therein. Anotherlimitation is that the annular passageway may be disturbed if there is abend in the infusion section of the tube. A bend in the catheter maydeform the annular passageway or even cause the inner and outer tubes tocome into contact. This can cause an uneven fluid pressure within alongitudinal cross-section of the annular passageway, resulting innon-uniform fluid delivery.

[0012] Thus, there is a need for an improved infusion catheter fordelivering fluid medication uniformly along its infusion section in arelatively simple, easy to manufacture design which is effective forboth high flow rate and low flow rate fluid delivery. Furthermore, it isrecognized that a particular class of catheters, such as the Wangcatheter, may provide uniform fluid delivery only at high fluid pressureor flow rates. However, there is a need for an infusion catheterbelonging to this class that has a relatively simple, easy tomanufacture design and can maintain uniform fluid delivery while bent orotherwise physically deformed.

SUMMARY OF THE INVENTION

[0013] Accordingly, it is a principle object and advantage of thepresent invention to overcome some or all of these limitations and toprovide an improved catheter for delivering fluid medication to a woundarea of an anatomical region.

[0014] In accordance with one embodiment the present invention acatheter is provided for the uniform delivery of fluid across ananatomical region, comprising an elongated tubular member made of aporous membrane. The membrane is sized to be inserted through asubcutaneous layer surrounding the anatomical region, such as a person'sskin. The membrane is configured so that a fluid introduced underpressure into an open end of the tubular member will flow through sidewalls of the tubular member at a substantially uniform rate along alength of the tubular member. The present invention also provides amethod of uniformly delivering fluid throughout an anatomical region,comprising the steps of inserting the elongated tubular member into theanatomical region and introducing a fluid under pressure into an openend of the tubular member.

[0015] Another embodiment of the present invention provides a catheterand method for the uniform delivery of fluid throughout an anatomicalregion. The catheter comprises an elongated support and a porousmembrane wrapped around the support. The support is configured so thatone or more lumens are formed between the support and the membrane.Alternatively, the support may be a tubular member having a plurality ofholes therein. The method comprises the steps of inserting theabove-described catheter into the anatomical region and introducing afluid under pressure into the proximal end of at least one of thelumens. Advantageously, the fluid passes through the membrane at asubstantially uniform rate into the anatomical region. The presentinvention further provides a method of manufacturing this cathetercomprising the steps of forming an elongated support and wrapping aporous membrane around the support so that one or more lumens are formedbetween the support and the membrane.

[0016] Another embodiment of the present invention provides a catheterand method for the uniform delivery of fluid throughout an anatomicalregion. The catheter comprises an elongated tube including a pluralityof exit holes along a length thereof and a tubular porous membraneconcentrically enclosed within the tube. The tube and membrane define alumen. The method comprises the steps of inserting the above-mentionedcatheter into the anatomical region and introducing a fluid underpressure into the proximal end of the lumen so that the fluidadvantageously passes through the membrane and the exit holes at asubstantially uniform rate into the anatomical region. The presentinvention further provides a method of manufacturing this catheter,comprising the steps of forming an elongated tube, providing a pluralityof exit holes along a length of the tube, forming a tubular porousmembrane, and concentrically enclosing the tubular porous membranewithin the tube so that the tube and membrane define a lumen.

[0017] Yet another embodiment of the present invention provides a deviceand method for the uniform delivery of fluid throughout an anatomicalregion. The device is advantageously simple and easy to manufacture,comprising an elongated catheter having a plurality of exit holes alonga length thereof. The exit holes may serve as the flow-restrictingorifice. Alternatively, a flow-restricting orifice may be providedelsewhere within the catheter or proximal to the catheter. The exitholes may gradually increase in size along the length of the catheter,so that the largest exit hole is fturther distal than the smallest exithole. Alternatively, the holes can be laser drilled and be ofapproximately the same size. Advantageously, a fluid flowing underpressure within the catheter will flow through substantially all of theexit holes at a substantially equal rate. The method comprises the stepsof inserting the catheter into the anatomical region and introducing afluid under pressure into the proximal end of the catheter. The fluidflows through the exit holes and enters the anatomical region,advantageously flowing through substantially all of the exit holes at asubstantially equal rate. The present invention further provides amethod of manufacturing this device, comprising the steps of forming anelongated catheter and providing a plurality of exit holes along alength of the catheter in a manner so that the exit holes graduallyincrease in size along the length of the catheter from the proximal endto the distal end thereof.

[0018] Yet another embodiment of the present invention provides acatheter and method for delivering fluid medication to an anatomicalregion. The catheter comprises a tube, a “weeping” tubular coil springattached to a distal end of the tube, and a stop closing a distal end ofthe spring. The tube and spring each define a portion of a centrallumen. The spring has adjacent coils in contact with one another so thatfluid within the spring and below a threshold dispensation pressure isprevented from exiting the lumen by flowing radially between the coils.The spring has the property of stretching when the fluid pressure isgreater than or equal to the threshold dispensation pressure permittingthe fluid to be dispensed from the lumen by flowing radially between thecoils, i.e. “weeping” through the spring. Alternatively, the fluid mayweep through imperfections in the spring coil. Advantageously, the fluidis dispensed substantially uniformly throughout the length andcircumference of a portion of the spring. In use, fluid is introducedinto an open proximal end of the tube, allowed to flow into the spring,and brought to a pressure greater than or equal to the thresholddispensation pressure so that the fluid weeps through the spring.

[0019] Yet another embodiment of the present invention provides acatheter and method for delivering fluid medication to an anatomicalregion. The catheter comprises a distally closed tube and a “weeping”tubular coil spring, as described above, concentrically enclosed withinthe tube. A plurality of exit holes are provided in side walls along alength of the tube, defining an infusion section of the tube. The springis enclosed within the infusion section so that a lumen is definedwithin the tube and spring. In use, fluid is introduced into a proximalend of the tube, allowed to flow into the spring, and brought to apressure greater than or equal to the threshold dispensation pressure ofthe spring so that the fluid is dispensed from the lumen by weepingthrough the spring and then flowing through the exit holes of the tube.

[0020] Yet another embodiment of the present invention provides acatheter comprising an elongated tube and a solid flexible memberpositioned within the tube. The tube has a closed distal end and aplurality of exit holes in side walls of the tube. The exit holes areprovided along a length of the tube defining an infusion section of thecatheter. The tube is sized to be inserted into an anatomical region.The member is positioned within the tube and is sized so that an annularspace is formed between the tube and the member. The member is formed ofa porous material. Advantageously, the catheter is configured so that afluid introduced into a proximal end of the tube will flow through theexit holes at a substantially uniform rate throughout the infusionsection.

[0021] In yet another embodiment, the present invention provides acatheter comprising an elongated tube having a plurality of exit slotsin side walls of the tube. The slots are provided along a length of thetube defining an infusion section of the catheter. The exit slots areoriented generally parallel to the longitudinal axis of the tube.Advantageously, the tube is configured so that a fluid flowing thereinwill flow through substantially all of the exit slots at a substantiallyequal rate. In one optional aspect, the slots increase in length fromthe proximal to the distal ends of the infusion section.

[0022] For purposes of summarizing the invention and the advantagesachieved over the prior art, certain objects and advantages of theinvention have been described herein above. Of course, it is to beunderstood that not necessarily all such objects or advantages may beachieved in accordance with any particular embodiment of the invention.Thus, for example, those skilled in the art will recognize that theinvention may be embodied or carried out in a manner that achieves oroptimizes one advantage or group of advantages as taught herein withoutnecessarily achieving other objects or advantages as may be taught orsuggested herein.

[0023] All of these embodiments are intended to be within the scope ofthe invention herein disclosed. These and other embodiments of thepresent invention will become readily apparent to those skilled in theart from the following detailed description of the preferred embodimentshaving reference to the attached figures, the invention not beinglimited to any particular preferred embodiment(s) disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0024]FIG. 1 is a schematic side view of a catheter having features andadvantages in accordance with a first embodiment of the presentinvention;

[0025]FIG. 2 is a sectional view of the catheter of FIG. 1, taken alongline 2-2 of FIG. 1;

[0026]FIG. 3 is a sectional view of the catheter of FIG. 1, taken alongline 3-3 of FIG. 1;

[0027]FIG. 4 is a perspective view of the end portion and support beamof the catheter of FIG. 1, illustrating a cross-section taken along line4-4 of FIG. 1;

[0028]FIG. 5 is a side view of a catheter having features and advantagesin accordance with a second embodiment of the present invention;

[0029]FIG. 6 is a cross-sectional view of the infusion section of thecatheter of FIG. 5 taken along line 6-6 of FIG. 5;

[0030]FIG. 7 is a cross-sectional view of a catheter having features andadvantages in accordance with a third embodiment of the presentinvention;

[0031]FIG. 8 is a side view of a catheter having features and advantagesin accordance with a fourth embodiment of the present invention;

[0032]FIG. 9 is a side view of a catheter having features and advantagesin accordance with a fifth embodiment of the present invention;

[0033]FIG. 10A is a cross-sectional view of the catheter of FIG. 9,illustrating an unstretched state of the spring;

[0034]FIG. 10B is a cross-sectional view of the catheter of FIG. 9,illustrating a stretched state of the spring;

[0035]FIG. 11 is a cross-sectional view of a catheter having featuresand advantages in accordance with a sixth embodiment of the presentinvention;

[0036]FIG. 12 is a side view of a catheter having features andadvantages in accordance with the sixth embodiment of the presentinvention;

[0037]FIG. 13 is a longitudinal cross-sectional view of a catheterhaving features and advantages in accordance with the seventh embodimentof the present invention;

[0038]FIGS. 14-16 are longitudinal cross-sectional views of catheterssimilar to that of FIG. 13, illustrating alternative attachments betweenthe internal porous member and the tube;

[0039]FIG. 17 is a transverse cross-sectional view of a catheteraccording to FIGS. 13-16, wherein the internal porous member isconcentric with the outer tube;

[0040]FIG. 18 is a transverse cross-sectional view of a catheteraccording to FIGS. 13-16, wherein the internal porous member is notconcentric with the outer tube;

[0041]FIG. 19 is a schematic illustration of a catheter of the presentinvention used in conjunction with an air eliminating filter;

[0042]FIG. 20 is a side view of a catheter having features andadvantages in accordance with the eighth embodiment of the presentinvention;

[0043]FIG. 21 is a side view of a catheter having features andadvantages in accordance with the ninth embodiment of the presentinvention; and

[0044]FIG. 22 is a schematic illustration of the use of a catheter ofthe present invention for treating a blood clot.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045]FIGS. 1-4 illustrate an infusion catheter 20 according to oneembodiment of the present invention. Catheter 20 preferably includes aflexible support 22 (FIGS. 2-4), a non-porous membrane 24, and a porousmembrane 26. The membranes 24 and 26 are wrapped around the support 22to form a plurality of axial lumens between the inner surfaces of themembranes 24 and 26 and the surface of the support 22, as described ingreater detail below. The non-porous membrane 24 defines a non-infusingsection 28 of the catheter 20, and preferably covers the support 22 fromthe proximal end thereof to a point 30, shown in FIG. 1. Similarly, theporous membrane 26 defines an infusion section 32 of catheter 20, andpreferably covers the support 22 from the point 30 to the distal end ofsupport 22. Alternatively, the catheter 20 may be configured without anon-porous membrane 24. In this configuration, the porous membrane 26covers the entire length of the support 22, so that the entire length ofthe support 22 corresponds to the infusion section of the catheter 20.The infusion section can have any desired length. The proximal end ofthe catheter 20 may be connected to a fluid supply 34 containing a fluid36 such as a liquid medication. The distal end of catheter 20 mayinclude a cap 48 (FIG. 4) defining the endpoint of the axial lumenswithin the catheter 20.

[0046] In use, the catheter 20 is inserted into an anatomical system,such as a human body, to deliver fluid medication directly to a woundarea within the anatomical system. In particular, the catheter 20 isdesigned to deliver medication throughout a generally linear segment ofthe wound area, corresponding to the infusion section 32 of the catheter20. Thus, the catheter is preferably inserted so that the infusionsection 32 is positioned within the wound area. By using well knownmethods, a physician or nurse may insert the catheter 20 with the aid ofan axial guide wire 46 positioned within an axial guide wire lumen 44 ofthe catheter. Once the catheter is positioned as desired, the guide wire46 is simply pulled back out through the proximal end of the catheter20. Alternatively, the catheter 20 may be provided without a guide wireor a guide wire lumen.

[0047]FIGS. 2 and 3 illustrate a preferred configuration of the support22. The surface of the support 22 includes interruptions such as aplurality of ribs 40 as shown in the figures. The interruptions areconfigured so that when the membranes 24 and 26 are wrapped around thesupport 22, the membranes form a portion of the walls of a plurality ofaxial lumens 38 within which the fluid 36 may flow. In a preferredconfiguration, a plurality of ribs 40 extend radially from a commonaxial center portion 42 of the support 22. The ribs 40 also extendlongitudinally along a length of the support 22, and preferably alongthe entire length thereof. In the non-infusing section 28, shown in FIG.2, the non-porous membrane 24 is preferably tightly wrapped around theouter edges of the ribs 40. As a result, the axial lumens 38 are formedbetween the inner surface of the non-porous membrane 24 and the outersurface of support 22. Similarly, in the infusion section 32, shown inFIG. 3, the porous membrane 26 is preferably tightly wrapped around theouter edges of the ribs 40, so that the axial lumens 38 are formedbetween the inner surface of porous membrane 26 and the outer surface ofsupport 22.

[0048] In an alternative embodiment of the catheter 20, the porousmembrane 26 may be wrapped around the entire length of the support 20,thus replacing the non-porous membrane 24. In this embodiment, theentire length of the support 22 corresponds to the infusion section 32.According to another alternative embodiment, the support 22 may extendonly within the infusion section 32, and a tube may be providedextending from the fluid supply 34 to the proximal end of the support22. In this embodiment, the tube replaces the non-porous membrane 24 andthe portion of the support 22 extending within the non-infusing section28 of the preferred embodiment. In other words, the tube defines thenon-infusing section 28.

[0049] In the preferred configuration, the number of ribs 40 equals thenumber of axial lumens 38. Although five ribs 40 and axial lumens 38 areshown in FIGS. 2 and 3, any suitable number of ribs 40 and lumens 38 maybe provided, giving due consideration to the goals of providing aplurality of lumens within the catheter 20, maintaining flexibility,and, if desired, maintaining the fluid independence of the lumens.Herein, the terms “fluid independence,” “fluid separation,” and thelike, when used to describe a plurality of axial lumens, simply meanthat the lumens do not fluidly communicate with each other. Themembranes 24 and 26 are preferably glued along the outer edges of theribs 40, utilizing any suitable glue, such as a medical grade glue orepoxy. This prevents the membranes 24 and 26 from slipping, which mightoccur as the catheter is inserted or removed from the anatomy. Morepreferably, the membranes are glued along the entire length of the outeredges of each of the ribs 40. Alternatively, the membrane may be wrappedaround the support and not secured to the support by a foreignsubstance. The membrane and support may also be secured to each other byother means known to those of skill in the art. This maintains the fluidindependence of the lumens 38. If desired, an axial guide wire lumen 44may be provided within the axial central portion 42 of the support 22.The guide wire lumen 44 is adapted to receive a guide wire 46 which maybe used to aid in the insertion of the catheter 20 into the anatomy, asdescribed above and as will be easily understood by those of skill inthe art.

[0050] As shown in FIG. 4, the catheter 20 preferably includes an endportion or cap 48 secured to the distal end of support 22. End portion48 may be formed integrally with the support 22 or may be adhesivelybonded thereto. Preferably, the proximal end of end portion 48 iscircular and has a diameter such that the outer surface of the proximalend of end portion 48 is aligned with the outer edges of the ribs 40 ofthe support 22, as shown. The porous membrane 26 is wrapped around theproximal end of the end portion 48. The membrane 26 is preferably gluedto the end portion 48 so that fluid 36 within the lumens 38 is preventedfrom exiting the catheter 20 without passing through the walls of themembrane 26. End portion 48 blocks axial fluid flow through the distalend of catheter 20. However, end portion 48 may optionally be formedfrom a porous material to permit some axial dispensation of fluid fromthe distal end of the catheter 20, if desired. The distal end of endportion 48 is preferably dome-shaped, as shown, to permit the catheter20 to more easily be inserted into an anatomical region.

[0051] The support 22 can be formed from a variety of materials, givingdue consideration to the goals of flexibility, light-weight, strength,smoothness, and non-reactivity to anatomical systems, i.e., safety.Suitable materials for the support 22 include nylon, polyamide, teflon,and other materials known to those skilled in the art. The porousmembrane 26 is preferably a sponge-like or foam-like material or ahollow fiber. The membrane 26 may be formed from a variety of suitablematerials, giving due consideration to the goals of being flexible andnon-reactive to anatomical systems. The membrane 26 preferably has aporosity resulting in substantially uniform dispensation of fluid alongthe surface area of the infusion section 32 of the catheter 20, and hasan average pore size sufficiently small to limit the flow of bacteriathrough the membrane walls. Some suitable materials for the membrane 26are polyethylene, polysulfone, polyethersulfone, polypropylene,polyvinylidene difluoride, polycarbonate, nylon, or high densitypolyethylene. These materials are advantageously biocompatible. Theporous membrane 26 may filter out unwanted bacteria from the fluidmedication as it passes through the membrane 26. It is known that thesmallest bacteria cannot pass through a pore any smaller than 0.23microns. Thus, the average pore size, or pore diameter, of the porousmembrane 26 may be less than 0.23 microns to prevent bacteria fromtraversing the membrane 26. The average pore size, or pore diameter, ofthe membrane 26 is preferably within the range of about 0.1 to 1.2microns, more preferably within the range of about 0.3 to 1 micron, andeven more preferably about 0.8 microns.

[0052] As mentioned above, the proximal end of catheter 20 may beconnected to a fluid supply 34. The catheter 20 may be configured sothat each axial lumen 38 is fluidly independent. In other words, thelumens 38 would not fluidly communicate with one another. The catheter20 may be connected to a single fluid supply 34, so that the fluid 36flows within each of the lumens 38. Alternatively, the catheter 20 maybe connected to a plurality of separate fluid supplies so that severaldifferent fluids may separately flow within the lumens 38. According tothis configuration, each lumen 38 may be connected to a separate fluidsupply so that the total number of different fluids that may bedelivered to the anatomy is equal to the number of lumens 38.Alternatively, the fluid lumens need not be fluidly independent. Forexample, the membrane 26 may not be secured to the support 22 along theentire length of the support 22, thus permitting fluid 36 to migratebetween lumens 38.

[0053] In operation, the catheter 20 delivers fluid directly to the areaof the anatomy that is adjacent to the infusion section 32. The fluid 36from the fluid source 34 is introduced into the axial lumens 38 at theproximal end of the catheter 20. The fluid 36 initially flows throughthe non-infusing section 28. When the fluid 36 first reaches theinfusion section 32, it soaks into the porous membrane 26. As more fluid36 enters the infusion section 32, it diffuses longitudinally within thewalls of the membrane 26 until the entire membrane 26 and infusionsection 32 are saturated with fluid. At this point the fluid 36 beginsto pass through the membrane 26, thereby exiting the catheter 20 andentering the anatomy. Moreover, the fluid 36 advantageously passesthrough the entire surface area of the porous membrane 26 at asubstantially uniform rate, due to the characteristics of the membrane26. Thus, the fluid is delivered at a substantially equal ratethroughout a generally linear segment of the wound area of the anatomy.Furthermore, this advantage is obtained for both low and high pressurefluid delivery.

[0054]FIGS. 5 and 6 illustrate a catheter 50 according to an alternativeembodiment of the present invention. According to this embodiment, thecatheter 50 includes an elongated outer tube 52 and an inner elongatedtubular porous membrane 54. The tubular membrane 54 is preferablyconcentrically enclosed within the outer tube 52. More preferably, thetube 52 tightly surrounds and supports the tubular membrane 54 so that arelatively tight fit is achieved between the inner dimensions of tube 52and the outer dimensions of membrane 54. A plurality of fluid exit holes56 are provided within the tube 52, preferably throughout the entirecircumference thereof. The portion of tube 52 that includes the exitholes 56 defines the infusion section of catheter 50. The tubularmembrane 54 need only be provided along the length of the infusionsection, but could be longer. Optionally, axial exit holes may beprovided within the distal tip 58 of the tube 52. Also, a guide wireand/or guide wire lumen may be provided to aid in the insertion of thecatheter 50 into the anatomy, as will be understood by those skilled inthe art.

[0055] The tube 52 may be formed from any of a variety of suitablematerials, such as nylon, polyimide, teflon and other materials known tothose skilled in the art, giving due consideration to the goals ofnon-reactivity to anatomical systems, flexibility, light-weight,strength, smoothness, and safety. In a preferred configuration, the tube52 is preferably a 20 gauge catheter tube, having inside and outsidediameters of 0.019 inches and 0.031 inches, respectively. The exit holes56 of tube 52 are preferably about 0.015 inches in diameter and providedat equally spaced axial positions along the tube 52. The holes 56 arepreferably arranged so that every hole is angularly displaced about 120°relative to the longitudinal axis of the tube 52, from the angularlocation of the previous hole. The axial separation between adjacentexit holes 56 is preferably within the range of about 0.125 to 0.25inches, and more preferably about {fraction (3/16)} inch. Also, theinfusion section can have any desirable length. This configurationresults in a thorough, uniform delivery of fluid throughout a generallylinear segment of the wound area. Of course, the exit holes 56 may beprovided in any of a variety of alternative arrangements.

[0056] The tubular porous membrane 54 is preferably a sponge-like orfoam-like material or a hollow fiber. The tubular membrane 54 may havean average pore size, or pore diameter, less than 0.23 microns to filterbacteria. The pore diameter is preferably within the range of about 0.1to 1.2 microns, more preferably within the range of about 0.3 to 1micron, and even more preferably about 0.8 microns. The tubular membrane54 may be formed from any of a variety of suitable materials, giving dueconsideration to the goals of non-reactivity to anatomical systems,maintaining flexibility, fitting within the size constraints of the tube52, and having a porosity resulting in the substantially uniformdispensation of fluid through all of the exit holes 56 in tube 52. Somesuitable materials for the membrane 54 are polyethylene, polysulfone,polyethersulfone, polypropylene, polyvinylidene difluoride,polycarbonate, nylon, or high density polyethylene. Preferable insideand outside diameters of the tubular membrane 54 are 0.010 inches and0.018 inches, respectively. In the event that a guide wire 46 isprovided, the guide wire may be a stainless steel wire about 0.005inches in diameter. The tube 52 may be secured to the membrane 54 byepoxy or other means known to those skilled in the art. Alternatively,the membrane 54 may contact the tube 52 with an interference fit and notuse other materials to secure the membrane 54 in the tube 52.

[0057] In operation, the catheter 50 delivers fluid to the region of ananatomical system adjacent to the infusion section of catheter 50. Asthe fluid flows into the infusion section, it initially soaks into thetubular porous membrane 54. As more fluid enters the infusion section,the fluid diffuses longitudinally within the walls of the tubular member54. Once the membrane 54 and the tubular space therein are saturated,the fluid passes through the membrane 54 and exits the catheter 50 byflowing through the exit holes 56 of the tube 52. Moreover, the fluidadvantageously passes through the membrane substantially uniformlythroughout the surface area of the membrane 54, resulting in asubstantially uniform flow through substantially all of the exit holes56. Thus, the fluid is delivered at a substantially equal ratethroughout the wound area of the anatomy. Furthermore, this advantage isobtained for both low and high pressure fluid delivery.

[0058]FIG. 7 illustrates a catheter 70 according to another embodimentof the present invention. Catheter 70 includes a tube 72 having aplurality of exit holes 76 in side walls of the tube, and a tubularporous membrane 74 concentrically enclosing the tube 72. Catheter 70operates in a similar manner to catheter 50 described above inconnection with FIGS. 5 and 6. In use, fluid medication passes throughthe exit holes 76 and then begins to soak into the porous membrane 74.The fluid diffuses longitudinally within the walls of the membrane untilthe membrane is saturated. Thereafter, the fluid leaves the membranewalls and enters the anatomy. Advantageously, the fluid is dispensed tothe anatomy at a substantially uniform rate throughout the surface areaof the membrane 74. As in the previous embodiments, this advantage isobtained for both low and high pressure fluid delivery.

[0059]FIG. 8 illustrates a catheter 60 according to another embodimentof the present invention. Catheter 60 is better suited for relativelyhigh flow rate delivery of fluid to a region within an anatomicalsystem. Catheter 60 includes a tube 62 having a plurality of exit holes64 of increasing size. In particular, the more distal exit holes arelarger in diameter than the more proximal exit holes. The position ofthe exit holes 64 on the tube 62 defines the length of the infusionsection of the catheter 60. The infusion section can have any desiredlength. The proximal end of catheter 60 is connected to a fluid supply,and a guide wire and/or guide wire lumen may also be provided for aidingin the insertion of catheter 60 into the anatomy.

[0060] As discussed above, for high or low pressure fluid delivery, exitholes nearer to the distal end of a catheter tube generally haveincreased flow resistance compared to exit holes nearer to the proximalend of the tube. Also, the fluid flowing through the more distal holesexperiences a greater pressure drop. Consequently, there is generally agreater flow rate of fluid through the more proximal holes, resulting innon-uniform fluid delivery. In contrast, catheter 60 advantageouslyprovides substantially uniform fluid delivery through substantially allof the exit holes 64, under relatively high flow rate conditions. Thisis because the larger size of the more distal holes compensates fortheir increased flow resistance and pressure drop. In other words, sincethe more distal holes are larger than the more proximal holes, there isa greater flow rate through the more distal holes than there would be ifthey were the same size as the more proximal holes. Advantageously, theholes 64 are provided in a gradually increasing size which results insubstantially uniform fluid delivery. In addition, the exit holes 64 maybe sized so that they combine to form a flow-restricting orifice, asdescribed below in connection with the embodiment of FIG. 12.

[0061] As compared to prior art catheters, catheter 60 is advantageouslysimple and easy to manufacture. All that is required is to drill aplurality of exit holes 64 in the tube 62. Furthermore, catheter 60 cansustain greater bending than prior art catheters while maintainingoperability. In contrast to prior art catheters, such as the Wangcatheter, if the tube 62 is bent somewhat, it will still deliver fluidrelatively uniformly. This is because the tube 62 has a single lumenwith a relatively large cross-section. When the tube 62 is somewhatbent, fluid flowing within the lumen is less likely to experienceblockage and a consequent pressure change which might lead tonon-uniform fluid dispensation.

[0062] The tube 62 of catheter 60 may be formed from any of a widevariety of materials, giving due consideration to the goals ofnon-reactivity to anatomical systems, flexibility, light-weight,strength, smoothness, and safety. Suitable materials include nylon,polyimide, teflon, and other materials known to those skilled in theart. The infusion section can have any desired length but is preferablyabout 0.5 to 20 inches long, and more preferably about 10 inches long.The diameter of the exit holes 64 preferably ranges from about 0.0002inches at the proximal end of the infusion section to about 0.01 inchesat the distal end thereof. The largest, i.e., most distal, exit hole 64is preferably about 0.25 inches from the distal end of the tube 62. Inthe preferred configuration, the axial separation between adjacent holes64 is within the range of about 0.125 to 0.25 inches, and morepreferably about {fraction (3/16)} inch. Optionally, the holes 64 may beprovided so that adjacent holes are angularly displaced by about 120□ asin the embodiment of FIG. 5. Of course, if too many exit holes 64 areprovided, the tube 62 may be undesirably weakened.

[0063]FIGS. 9, 10A, and 10B illustrate a catheter 80 according toanother embodiment of the present invention. The catheter 80 comprises atube 82, a “weeping” tubular coil spring 84, and a stop 86. The proximalend of the spring 84 is attached to the distal end of the tube 82 sothat the tube and spring each define a portion of a central lumen. Apreferably dome-shaped stop 86 is attached to and closes the distal endof the spring 84. The portion of the spring 84 that is distal to thetube 82 comprises the infusion section of the catheter 80. In anunstretched state, shown in FIG. 10A, the spring 84 has adjacent coilsin contact with one another so that fluid within the spring and below athreshold dispensation pressure is prevented from exiting the lumen byflowing radially between the coils. The spring 84 has the property ofstretching longitudinally, as shown in FIG. 10B, when the fluid pressureis greater than or equal to the threshold dispensation pressure of thespring, thereby permitting the fluid to be dispensed from the lumen by“weeping,” i.e., leaking radially outward between the coils.Alternatively, the spring may stretch radially without elongating topermit fluid to weep through the coils of the spring. Further, thespring may stretch both longitudinally and radially to permit weeping,as will be understood by those of skill in the art. Advantageously, thefluid between the coils of the spring is dispensed substantiallyuniformly throughout the length and circumference of the portion of thespring that is distal to the tube 82, i.e., the infusion section. Thecatheter 80 can be used for both high or low flow rate fluid delivery.

[0064] In use, the catheter 80 is inserted into an anatomical region sothat the spring 84 is in a region to which fluid medication is desiredto be delivered. The spring is initially in an unstretched state, asshown in FIG. 10A. The fluid is introduced into a proximal end of thetube 82 of the catheter 80 and flows into and through the spring 84until it reaches the stop 86. As fluid is continually introduced intothe proximal end of the tube 82, the fluid builds inside of the spring84. When the spring 84 is filled with fluid, the fluid pressure risesmore quickly. The fluid imparts a force directed radially outward ontothe spring coils. As the pressure builds, the outward force becomeslarger. Once the fluid pressure rises to the threshold dispensationpressure, the outward force causes the spring coils to separate slightlyso that the spring stretches longitudinally, as shown in FIG. 10B.Alternatively, the coils may separate radially, as discussed above. Thefluid then flows through the separated coils to be dispensed from thecatheter 80. Moreover, the dispensation is advantageously uniformthroughout the infusion section of the catheter 80. As fluid iscontinually introduced into the tube 82, the spring 84 remains stretchedto continually dispense fluid to the desired region within the anatomy.If the fluid introduction temporarily ceases, the fluid pressure withinthe spring 84 may fall below the threshold dispensation pressure. If so,the spring will compress so that the coils are once again adjacent andthe fluid is no longer dispensed.

[0065] Several spring types will achieve the purposes of this invention.Suitable spring types are 316L or 402L, which can be readily purchased.In a preferred configuration, the spring 84 has about 200 coils per inchalong its length. In this configuration, the spring can advantageouslysustain a high degree of bending without leaking fluid from within, andonly a severe bend will cause adjacent coils to separate. Thus, thespring 84 may be flexed considerably within an anatomical region withoutcausing fluid to leak and therefore be dispensed to only one regionwithin the anatomy. The spring 84 can have any desired length to definethe length of the infusion section of the catheter 80. The spring may beformed from a variety of materials, giving due consideration to thegoals of strength, flexibility, and safety. A preferred material isstainless steel. In the preferred configuration, the inside and outsidediameters of the spring are about 0.02 inches and 0.03 inches,respectively, and the spring wire has a diameter of about 0.005 inches.The proximal end of the spring 84 is preferably concentrically enclosedwithin the distal end of the tube 82. The spring can be glued to theinside wall of the tube 82 using, for example, a U.V. adhesive, apotting material, or other bonding materials. Alternatively, the springcan be soldered within the tube 82 or be fitted with a proximal plug andtightly plugged into the tube 82.

[0066] The tube 82 and stop 86 can be formed from any of a variety ofmaterials, giving due consideration to the goals of flexibility,light-weight, strength, smoothness, and safety. Suitable materialsinclude nylon, polyimide, teflon, and other materials known to thoseskilled in the art.

[0067]FIG. 11 illustrates a catheter 90 according to another embodimentof the present invention. The catheter 90 comprises a distally closedtube 92 and a “weeping” tubular coil spring 94 concentrically enclosedwithin the tube 92 so that a lumen is defined within the tube andspring. A plurality of exit holes 96 are provided along a length of thetube 92, in the side wall thereof. The length of the tube 92 includingsuch exit holes 96 defines an infusion section of the catheter 90. Theexit holes 96 are preferably provided throughout the walls of theinfusion section. The infusion section can have any desired length. Inthe preferred configuration, the axial spacing between adjacent holes 96is within the range of about 0.125 to 0.25 inches, and more preferablyabout {fraction (3/16)} inch. Adjacent holes 96 are preferably angularlyspaced apart by about 120o. The spring 94 is preferably enclosed withinthe infusion section of the catheter and configured similarly to thespring 84 of the embodiment of FIGS. 9, 10A and 10B. The spring 94 ispreferably longer than the infusion portion and positioned so that allof the exit holes 96 are adjacent to the spring 94. In thisconfiguration, the fluid is prevented from exiting the lumen withoutflowing between the spring coils. A stop is preferably attached to thetube to close the distal end thereof. Alternatively, the tube 92 may beformed with a closed distal end. The catheter 90 can be used for high orlow flow rate fluid delivery.

[0068] In use, the catheter 90 is inserted into an anatomical region sothat the infusion section is in a region to which fluid medication isdesired to be delivered. The fluid is introduced into a proximal end ofthe tube 92 of the catheter 90 and flows through the spring 94 until itreaches the closed distal end of the tube 92. As fluid is continuallyintroduced into the proximal end of the tube 92, the fluid builds insideof the spring 94. Eventually, the spring 94 becomes filled with fluid,the fluid pressure rises, and the fluid weeps through the spring coilsas described above in connection with the embodiment of FIGS. 9, 1 OA,and 1 OB. Moreover, the fluid flows through the spring coilssubstantially uniformly throughout the length and circumference of thespring 94. The fluid then exits the tube 92 by flowing through the exitholes 96 of the infusion section. The exit holes are preferably equal insize so that the fluid flows at a substantially equal rate through theexit holes, advantageously resulting in a generally uniform distributionof fluid throughout a desired region of the anatomy. As fluid iscontinually introduced into the catheter 90, the spring 94 remainsstretched to continually dispense fluid from the catheter. If the fluidintroduction ceases temporarily, the fluid pressure within the spring 94may fall below the threshold dispensation pressure. If so, the springmay compress so that the coils are once again adjacent and the fluid isno longer dispensed.

[0069] In the preferred configuration, the spring 94 and tube 92 are incontact along the entire length of the spring, so that the fluid weepingthrough the spring is forced to flow through the holes 96 of theinfusion section. Preferably, one end of the spring 94 is attached tothe inside walls of the tube 92, permitting the other end of the springto be displaced as the spring stretches. The spring can be glued to thetube 92 with, for example, a U.V. adhesive, potting material, or otherbonding materials. Alternatively, an end of the spring can be solderedonto the inner walls of the tube 92. The tube 92 can be formed from anysuitable material. The inside walls of the tube 92 are preferably smoothso that the spring can more freely stretch and compress.

[0070]FIG. 12 illustrates a catheter 100 according to another embodimentof the present invention. The catheter 100 comprises a distally closedtube 102 having a plurality of exit holes 104 in side walls of the tube102. The portion of the tube 102 having exit holes 104 defines aninfusion section of the catheter 100. The exit holes 104 are sized tohave a combined area of opening that is smaller than the area of anyother flow-restricting cross-section or orifice of the catheter. Thus,the exit holes 104 are the flow-restrictor of the catheter 100. In use,the catheter advantageously dispenses fluid through substantially all ofthe exit holes 104. A fluid introduced into a proximal end of the tube102 flows through the tube until it reaches the closed distal endthereof. At this point, the fluid builds within the infusion portion ofthe catheter. The fluid is substantially prevented from flowing throughthe holes 104, due to their small size. Eventually, the infusion portionof the catheter becomes filled with fluid. As fluid is continuallyintroduced into the proximal end of the tube 102, the fluid pressurebegins to build. At some point the pressure becomes sufficiently high toforce the fluid through the exit holes 104. Moreover, the fluid flowsthrough substantially all of the exit holes 104.

[0071] In this preferred configuration, the exit holes 104 are all equalin size so that the fluid is dispensed at a substantially equal ratethrough substantially all of the holes. The holes 104 are preferablylaser drilled to achieve a very small hole diameter. A preferreddiameter of the exit holes 104 is about 0.0002 inches, or about 5microns. Numerous exit holes 104 may be provided within the tube 102.The holes are advantageously provided throughout the circumference ofthe infusion portion of the catheter 100, to more uniformly deliver thefluid throughout an anatomical region. A preferred axial spacing betweenadjacent holes 104 is within the range of about 0.125 to 0.25 inches,and more preferably about {fraction (3/16)} inch. The catheter 100 canbe used for high or low flow rate fluid delivery. The tube 102 can beformed from any of a variety of materials known to those skilled in theart and discussed previously.

[0072]FIG. 13 illustrates a catheter 200 according to another embodimentof the present invention. Catheter 200 includes a distally closed tube202 having a plurality of exit holes 204 therein along an infusionsection of the catheter, as in the above-described embodiments. Theholes 204 are desirably provided throughout the circumference of thetube 202. Enclosed within the tube 202 is an elongated member 206 formedof a porous material. Preferably, the member 206 is generallycylindrical in shape, and solid. Preferably, the member 206 ispositioned within the tube 204 so that an annular space 208 is formedbetween the outer surface of the member 206 and the inner surface of thetube 202. Preferably, the member 206 extends from the distal end 210 ofthe tube 202 rearwardly to a point proximal of the infusion section ofthe catheter. Alternatively, the member 206 may extend along only aportion of the infusion section. The member 206 is preferably generallyconcentric with the tube 202, but non-concentric designs will achievethe advantages of the invention. Preferably, the member 206 ismanufactured of a flexible material to assist with the placement of thecatheter 200 in the body of a patient.

[0073] In operation, fluid medication flowing in the tube 202 saturatesthe porous member 206 and flows into the annular region 208. Once themember 206 is saturated, the fluid in the member 206 flows into theregion 208 and out of the catheter 200 through the exit holes 204.Advantageously, since the fluid pressure is uniform throughout theannular region 208, the fluid flows substantially uniformly through allof the holes 204. There are several advantages of the annular region208. One advantage is that it tends to optimize the uniformity of flowthrough the exit holes 204. Also, the member 206 may be formed from aporous material that tends to expand when saturated with liquid. If so,the member 206 preferably expands into the annular region 208 withoutpressing against the tube 202. This limits the possibility of highpressure regions at the interior surface of the tube 202, which couldcause uneven exit flow of the medication within the wound site.Alternatively, the member 206 may expand and come into contact with thetube 202, and still accomplish the goals of the present invention.

[0074] The member 206 is formed of a porous material having an averagepore size preferably within the range of 0.1-50 microns, and morepreferably about 0.45 microns. The radial width W of the annular region208 is preferably within the range of 0 to about 0.005 microns, and morepreferably about 0.003 microns. The member 206 can be formed of any of avariety of materials, giving due consideration to the goals of porosity,flexibility, strength, and durability. A preferred material is Mentek.

[0075] The member 206 can be secured within the tube 202 by the use ofan adhesive. In one embodiment, as shown in FIG. 13, the adhesive isapplied at the distal end of the member 206 to form a bond with theinterior surface of the distal end of the tube 202. Preferably, adhesiveis applied at or near the proximal end of the infusion section of thecatheter 200. Additionally, the adhesive can be applied to thecircumference of the member 206 at any longitudinal position thereof,forming a ring-shaped bond with the interior surface of the tube 202.For example, in the embodiment of FIG. 13, a ring-shaped bond 214 isprovided just proximal of the infusion section of the catheter 200.Other configurations are possible. For example, FIG. 14 shows anembodiment in which the adhesive is applied to the distal end of themember 206 to form a bond 216, and also at generally the center of theinfusion section to form a ring-shaped bond 218. FIG. 15 shows anembodiment in which the adhesive is applied only to the distal end ofthe member 206 to form a bond 220. FIG. 16 shows an embodiment in whichthe adhesive is applied only to the center of the infusion section toform a ring-shaped bond 222. Those of ordinary skill in the art willunderstand from the teachings herein that the adhesive may be applied inany of a variety of configurations. Thus, for example, adhesive at thedistal end of the catheter (i.e., 212, 216, and 220 in FIGS. 13, 14, and15, respectively) is not required.

[0076] In the current best mode of the invention, preferably two bondsare incorporated—one at the most proximal hole and one at the mostdistal hole of the catheter. Each bond is formed with an adhesive asdescribed below.

[0077] The ring-shaped bond 214 can be formed by pouring the adhesive inliquid form through one of the exit holes 204 when the member 206 is inthe tube 202. The adhesive, having a generally high viscosity, tends toflow about the circumference of the member 206, rather than into thebody of the member. The adhesive thus forms a ring-shaped bond with thetube 202, as will be understood by those of skill in the art. Also, theadhesive plugs the exit hole 204 through which it is poured. Any of avariety of different types of adhesives will be acceptable, a preferredadhesive being Loctite.

[0078] As mentioned above, the member 206 is preferably concentric withthe tube 202. FIG. 17 shows a cross-section of a catheter 200 in whichthe member 206 is concentrically enclosed within the tube 202.Alternatively, the member 206 may be positioned adjacent to the tube202, as shown in FIG. 18. The configuration of FIG. 18 may be easier tomanufacture than that of FIG. 17, since the member 206 does not have tobe centered within the tube 202.

[0079] Those of ordinary skill in the art will understand from theteachings herein that the member 206 can be of any desired length andcan extend along any desired length of the infusion section of thecatheter 200. For example, the member 206 does not have to extend to thedistal end of the tube 202. Further, the proximal end of the member 206may be either distal or proximal to the proximal end of the infusionsection.

[0080] When any of the catheters of the above embodiments is used, thecatheter may initially have air inside of the catheter tube. Forexample, the catheter 200 shown in FIG. 13 may have air inside of theporous material of the member 206. The introduction of liquid medicationinto the catheter forces the air to flow out of the exit holes. However,this may take several hours. If the catheter is inserted into a patientwhile air is inside, and liquid medication is introduced into thecatheter, the patient's wound site may receive little or no medicationuntil air is expelled from the catheter tube. Thus, it is preferred torun the liquid medication through the catheter prior to inserting thecatheter into a patient, to ensure that the air is expelled from thecatheter prior to use. Further, with reference to FIG. 19, an air filter224, as known in the art, can be inserted into the catheter tubingproximal the infusion section 226 of the catheter 200. The filter 224prevents undesirable air from entering the infusion section 226 of thecatheter 200.

[0081]FIGS. 20 and 21 illustrate catheter tubes having elongated exitholes or slots. These catheter tubes may be used in place of thecatheter tubes shown and described above. FIG. 20 shows a tube 230having exit holes or slots 232 that are elongated in the longitudinaldirection of the tube 230. The slots 232 are preferably providedthroughout the circumference of the tube 230, along the infusion sectionof the catheter. Compared to smaller exit holes, the elongated slots 232tend to increase the flowrate of fluid exiting the catheter, by reducingthe flow impedance experienced by the fluid. Preferably, the slots 232may be oriented longitudinally on the catheter body so as not tocompromise the structural integrity of the catheter 200, as will beeasily understood by those of skill in the art.

[0082]FIG. 21 shows a tube 234 having exit holes or slots 236 whoselengths increase along the length of the tube in the distal direction.In the illustrated embodiment, the slots nearer to the proximal end ofthe infusion section of the tube 234 are shorter in length than theslots nearer to the distal end of the infusion section. As in theembodiment of FIG. 8, the catheter tube 234 advantageously providessubstantially uniform fluid delivery through substantially all of theexit slots 236, under relatively high flow rate conditions. This isbecause the larger size of the more distal slots compensates for theirincreased flow resistance and pressure drop. In other words, since themore distal slots are larger than the more proximal slots, there is agreater flow rate through the more distal slots than there would be ifthey were the same size as the more proximal slots. Advantageously, theslots 236 are provided in a gradually increasing length, which resultsin substantially uniform fluid delivery. Further, the elongated slotsresult in generally higher exit flowrates, as in the embodiment of FIG.20.

[0083] With regard to all of the above embodiments of catheters, anindependent guide wire lumen may be provided within or adjacent to thelumen(s) disclosed, as will be understood by those skilled in the art.

[0084] The catheters of the present invention can be used in variousmedical applications. With reference to FIG. 22, in one exemplaryapplication a catheter 20 (reference numeral 20 is used to identify thecatheter, but any of the above-described catheters can be used) isinserted into a blood clot 240 inside of a vein or artery 242.Preferably, the infusion section of the catheter is within the bloodclot 240. Liquid medication is preferably introduced into the proximalend of the catheter tube. Advantageously, the medication exits thecatheter 20 at a uniform rate throughout the infusion section todissolve the clot 240.

[0085] As will be easily understood by those of skill in the art, any ofthe catheter embodiments described herein may be used in a variety ofapplications including, but not limited to, peripheral nerve blocks,intrathecal infusions, epideral infusions, intravascular infusions,intraarterial infusions and intraarticular infusions, as well as inwound site pain management.

[0086] In addition, any of the catheters disclosed herein may beintegral with a fluid line eminating from an infusion pump as opposed tobeing an independent catheter designed to be connected or secured to aninfusion pump.

[0087] Although this invention has been disclosed in the context ofcertain preferred embodiments and examples, it will be understood bythose skilled in the art that the present invention extends beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the invention and obvious modifications and equivalentsthereof. Thus, it is intended that the scope of the present inventionherein disclosed should not be limited by the particular disclosedembodiments described above, but should be determined only by a fairreading of the claims that follow.

What is claimed is:
 1. A catheter for the uniform delivery of fluidthroughout an anatomical region, comprising: an elongated tube having aclosed distal end and a plurality of exit holes in side walls of saidtube, said exit holes provided along a length of said tube defining aninfusion section of said catheter, said tube being sized to be insertedinto an anatomical region; and an elongated member positioned withinsaid tube, said member being sized so that an annular space is formedbetween said tube and said member, said member being formed of a porousmaterial; wherein said catheter is configured so that a fluid introducedinto a proximal end of said tube will flow through said exit holes at asubstantially uniform rate throughout said infusion section.
 2. Thecatheter of claim 1, wherein said member is concentric with said tube.3. The catheter of claim 1, wherein said member is not concentric withsaid tube.
 4. The catheter of claim 1, wherein said member is secured tosaid tube by a ring-shaped bond near the proximal end of said infusionsection.
 5. The catheter of claim 1, wherein said member is secured tosaid tube by a ring-shaped bond generally midway between the proximaland distal ends of said infusion section.
 6. The catheter of claim 1,wherein said member is bonded to said tube at the distal end of saidmember.
 7. The catheter of claim 1, wherein said porous material has anaverage pore size within the range of 0.1-50 microns.
 8. The catheter ofclaim 1, wherein said porous material is Mentek.
 9. The catheter ofclaim 1, wherein said annular space has a radial width within the rangeof 0-0.005 microns.
 10. The catheter of claim 1, further comprising anair filter in the flow path of said tube.